Dietary supplementation with fish oil induces depression of a variety of immune function parameters. Given the impossibility to control the intake of different fatty acids in volunteers following an open diet, we admitted two volunteers to the GCRC, where they received identical standard diets with known amounts of fatty acids for a six week period. One of the volunteers was given 10 g fish oil/day and the other 10 g of olive oil/day. Both completed the trial successfully, and we revised our application for funding to the NIH.